Remove unused user_spec
Remove unused user_spec

Part of refactoring is removing unused files/code. Since we don't have
any model tests yet, there isn't much point to keeping that file around.

chrisswk/example-rails-4-image-gallery,chrisswk/example-rails-4-image-gallery,chrisswk/example-rails-4-image-gallery,codeunion/example-rails-4-image-gallery,codeunion/example-rails-4-image-gallery